Modes
| Band | Frequency | Wavelength | Propagation via | |
|---|---|---|---|---|
| ELF | Extremely Low Frequency | 3–300 Hz | 1000-100,000 km | |
| VLF | Very Low Frequency | 3–30 kHz | 100–10 km | Guided between the earth and the ionosphere. |
| LF | Low Frequency | 30–300 kHz | 10–1 km | Guided between the earth and the D layer of the ionosphere.
Surface waves. |
| MF | Medium Frequency | 300–3000 kHz | 1000–100 m | Surface waves.
E, F layer ionospheric refraction at night, when D layer absorption weakens. |
| HF | High Frequency (Short Wave) | 3–30 MHz | 100–10 m | E layer ionospheric refraction.
F1, F2 layer ionospheric refraction. |
| VHF | Very High Frequency | 30–300 MHz | 10–1 m | Infrequent E ionospheric (Es) refraction. Uncommonly F2 layer ionospheric refraction during high sunspot activity up to 50 MHz and rarely to 80 MHz. Generally direct wave. Sometimes tropospheric ducting. |
| UHF | Ultra High Frequency | 300–3000 MHz | 100–10 cm | Direct wave. Sometimes tropospheric ducting. |
| SHF | Super High Frequency | 3–30 GHz | 10–1 cm | Direct wave. |
| EHF | Extremely High Frequency | 30–300 GHz | 10–1 mm | Direct wave limited by absorption. |
Read more about this topic: Radio Propagation
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